Site Productivity Index

Compare accounted standing+removed+mortality production to a caller age/area-compatible reference; unlike standing-volume MAI, removals and mortality are included, with no universal yield class.

Description

Biological production accounting includes standing volume, removals and mortality.

Biological production accounting includes standing volume, removals and mortality. Dividing that accounted production by age differs from using standing volume alone.^[1]

Compare accounted standing+removed+mortality production to a caller age/area-compatible reference; unlike standing-volume MAI, removals and mortality are included, with no universal yield class.

When to use Site Productivity Index

Use this tool to compare accounted standing+removed+mortality production to a caller age/area-compatible reference; unlike standing-volume MAI, removals and mortality are included, with no universal yield class.

Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.

How to use Site Productivity Index and understand its results

Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.
Enter currentStandingVolumeM3PerHa, cumulativeRemovedVolumeM3PerHa, cumulativeMortalityVolumeM3PerHa, standAgeYears, referenceAnnualProductionM3PerHa using the field table and calculation rules, then run the tool.
Read accountedAnnualBiologicalProductionM3PerHa, relativeSiteProductivityIndex. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
currentStandingVolumeM3PerHa	Current standing volume m3 per ha	number	Required
cumulativeRemovedVolumeM3PerHa	Cumulative removed volume m3 per ha	number	Required
cumulativeMortalityVolumeM3PerHa	Cumulative mortality volume m3 per ha	number	Required
standAgeYears	Stand age years	number	Required
referenceAnnualProductionM3PerHa	Reference annual production m3 per ha	number	Required

Use positive stand age and reference annual m³/ha production with nonnegative volume components in m³/ha. Return accounted annual production and its dimensionless ratio to the reference.

annual production=(standing+removed+mortality volume)/age; relative index=annual/reference production

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
accountedAnnualBiologicalProductionM3PerHa	Accounted annual biological production m3 per ha	number
relativeSiteProductivityIndex	Relative site productivity index	number

json

{
  "input": {
    "currentStandingVolumeM3PerHa": 100,
    "cumulativeRemovedVolumeM3PerHa": 30,
    "cumulativeMortalityVolumeM3PerHa": 20,
    "standAgeYears": 10,
    "referenceAnnualProductionM3PerHa": 10
  },
  "output": {
    "accountedAnnualBiologicalProductionM3PerHa": 15,
    "relativeSiteProductivityIndex": 1.5
  }
}

Limitations and assumptions

The reference must match the age/area basis. Unrecorded production and universal yield classes are not inferred.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Culmination Age MAI PAI: Audit sampled cumulative production through MAI and interval PAI, returning first age of sampled MAI maximum; distinct from existing one-interval increment formulas and no continuous unsampled peak inferred. For a complementary task, use Chapman-Richards Site Index Height Age: Normalize supplied dominant height/age to a reference-age Chapman–Richards site index with explicit growth/shape calibration; no generic height/age ratio or universal regional site table.

References

Site Productivity Index — tool.io

Similar or alternative tools

Culmination Age MAI PAI
Audit sampled cumulative production through MAI and interval PAI, returning first age of sampled MAI maximum; distinct from existing one-interval increment formulas and no continuous unsampled peak inferred.
Chapman-Richards Site Index Height Age
Normalize supplied dominant height/age to a reference-age Chapman–Richards site index with explicit growth/shape calibration; no generic height/age ratio or universal regional site table.